1. Field of the Invention
The present invention relates to the art of helical gear sizing and more particularly to an apparatus for and a method of sizing teeth profiles of helical gears that are in the form of a sintered powdery material, for example, for improving the precision or the like of the teeth profiles of the helical gears.
2. Description of the Prior Art
Hitherto, as a tooth profile sizing apparatus for sizing the teeth of helical gears having a non-linear tooth trace, for example, there has been known the technology as disclosed in Japanese patent publication No. H02-63634. The apparatus comprises an inner lower die on which a gear blank is disposed, an outer lower die adapted to engage or mesh with the teeth of the gear blank to size the gear profile thereof, an upper die for pressing the gear blank inwardly of the outer lower die, and a rotary driving mechanism adapted to rotate the outer lower die in synchronization with the descending movement of the upper die when the gear blank is pressed by the upper die, wherein the gear blank is pressed into and sized by the outer lower die in a compressed condition between the upper die and the inner lower die. When removing or taking the gear blank out of the dies, the upper die moves upwardly and the piston rod is pushed up to drive the inner lower die upwardly to thereby release the gear blank from the outer lower die. Then, the gear blank is pushed upwardly and released from the inner lower die by a knock-out pin.
The tooth profile sizing apparatus as described above, however, requires a long cycle time for the sizing process, and it especially takes much time until the sized product can be removed. Further, the construction for removing the product is comparatively complicated and incurs a large equipment cost.